This invention relates to continuous casting machines of the type designed to cast billets, blooms and slabs, for example, and more particularly to a continuous casting machine starting bar and starting bar storage system.
Continuous strands of cast metal, such as steel, are produced by pouring molten metal into the open upper end of a flow-through casting mold and withdrawing the metal in a continuous strand from the opening in the bottom of the mold. The molten metal is delivered to the upper end of the mold by a tundish, which in turn, receives metal from the ladle used to transport the metal from the melting furnace.
Initially, the lower end of the mold is closed by a starting bar which extends downwardly from the mold and through an arcuate guide assembly. When the end of the starting bar emerges from the open lower end of the mold, it is followed by the cast strand. As the joined ends of the cast product and starting bar move beyond the position of the withdrawal straightener mechanism rollers the two are disconnected by means of a separate mechanical device, so that the strand can pass to a runout table where it is cut into suitable lengths while the starting bar continues its movement along a separate path into its storage position.
Some prior art continuous casting machines employ in arcuate guiding system, located between the mold and withdrawal straightener mechanism, for the purpose of guiding the cast strand as it exits the mold in a generally downward direction along with providing support for the starting bar chain during commencement of the casting sequence along with providing support during insertion of the starting bar into position prior to the start of the casting process.
Two types of starting bars which satisfy this requirement are in common use. These include a rigid bar having a curvature which conforms to the arc described by the radius of the casting machine, and a flexible bar formed of a plurality of links which assume the contour of the support assembly through which it passes.
Examples of rigid curved starting bars are shown in U.S. Pat. Nos. 3,344,844; 3,370,641; 3,433,287; 3,628,595; 3,658,120; 3,930,533; 4,286,649; and 4,412,579. These bars may be fabricated as a unitary member or may be composed of a number or rigidly secured segments as shown in U.S. Pat. No. 4,043,383. Examples of flexible starting bars are shown in U.S. Pat. Nos. 3,426,835; 3,495,651; 4,291,748; 4,382,462; 4,425,960; and 4,457,353. Some prior art flexible starting bars are semi-rigid; that is, they are constructed and arranged to provide only a limited degree of flexibility as shown in U.S. Pats. Nos. 2,920,359; 3,608,619, and 4,383,571.
Each of the prior art casting machines discussed above requries a complicated and costly assembly for moving the starting bar away from the withdrawal rolls and for supporting the starting bar in its storage position. In addition, prior art starting bars are relatively complicated and expensive to manufacture. Further, prior art flexible starting bars require a curved guiding and supporting mechanism between the bottom of the mold and the entrance end of the withdrawal straightener unit, are expensive, and require costly and time consuming maintenance procedures int he event of a hot metal spill or a break out of a newly cast metal strand.